Power-transmission pulley



.637,402 J. ABBOTT cz minr 5 Patented Aug. 2, 1927.

'UNI'TED STAT l `,637,4o2* ES PATENT OFFICE.

GEOFFBEY JOSEPH ABBOTT, or LONDON, EN GLAND.

` 'rownn-'mavsmsson PULLEY;

Application filed October 9, 1926, Serial No. 140,637, and'in Great Britain November 11, 1925.

This invention relates to power transmission pulleys of the kind having oppositely inclined fianges such as are usually employed in Variable speed gears, the distance between the inclined fianges being adjusted to vary the effective diameter at whic'h'the fiexible driving member engages the pulley.

When such pulleys are intended for use with driving belts or chains having a series of laterally projecting Compound teeth each built up from a Variable number of metal plates adapted to slide across the length of the chain, depressions and projections are formed in the pulley flanges with which these driving teeth engage. manufacture of such pulley flanges has presented considerable difliculty, 4 since the grooves must be very accurately cut, the ribs on one flange must exactly register with the grooves on the opposite flange, and both flanges require case hardening after ,being cut and this hardening causes distortion and thus leads to inefiicient working of the gear, and the object of this invention is to provide a pulley of this type which will' work accurately when completed and which can be easily and cheaply made.

According to this invention each pulley flange comprises a relatively thin pressing or stamping having alternate ribs and depressions to engage the driving teeth of the chain or belt and a comparatively heavy reinforcing backing or support to impart the necessary lateral stability to the pres sing, this backing member being provided with a boss or its equivalent to receive the shaft on which the pulley is mounted.

- Each of these members can therefore be formed from the material best suited to the task it has to perform, so thatthe reinforcing backing or support may for nstance be of cast iron and a steel pressing, which can if desired be subsequently hardened, may be used for the working face of the pulley, grooves being either 'pressed up or machined on the surface. e two component members of each pulley flange are preferably connected together as for example by means of rivets, bolts or screws, or, if desired, they may be held together against relative rotary motion in a frictiona'l manner by the lateral pressure exerted by the ends of the compound driving teeth. r

Two constructional forms of the invention are illustrated by way of erample in the V accompanying" drawings, in which Hitherto the ing teeth engage,

the

' while .permitting Figure 2 shows a modified form of pulley face having teeth machined, on the surface of the pressed disc, and

Figure 3 is a 'longitudinal section through the pulley flange shownin Figure 1.

In the construction illustrated in Figures 1 and 3 the pulley flange comprises a vcast iron or like backing or support A havin a central boss A bored' to receive a pul ey shaft B and connected by a suitable number of arms, spokes or webs A to a relatively heavy rim A The actal working face of the pulley i. e. that with which the drivis in the form of a relatively thin steel or like pressing or stampin C having the necessary radial grooves G and projections C on 'its face, the stamping being dished or inclined as a whole to the required extent as shown so as to give the necessary inclination. Suitable seatings are formed for the underside of the pressing or stamping Con the inner face of the casting A. Thus, an annular bearing surface or seating D is conveniently formed by turning at D on the inner face of the rim A so' that the casting A and pressing or stamping C can be readily. and rigidly connected together by means of a series of bolts as shown at E. In'stead of bolts, rivets or screws may in some cases be employed to connect the pressng or stamping and the casting together. In the alternative construction shown in Figure 2, instead of the face part having the grooves and ribs pressed as in the construction shown in Figures 1 and 3, a pressed steel dish or saucer 0 is employed having the grooves machined on its outer face. This is secured by bolts, screws or. rivets as in the former construction.

The pulley flange formed in either of the above ways to ether with another similar flange to constitute a complete pulley are conveniently mounted on a common shaft having a feather B or like means which, relative movement of one or both flanges m the purpose of varying the elective diameter of the pulley, prevents their relative' rotary movement and thus ensures the grooves axial 'direction for the C on one pulley flange accurately registering with the ribs or projections 0 on the other fiange. Some known means are provided for varying the distance between the two fianges so as to Vary the effective diameter of' the pulley, such means comprising for example a member acting on one or each pulley fiange through a collar F and thrust bearing F g What I claim as my invention and desire to secure by Letters Patent is 1.' An expanding pulley comprising in combination a. pair of relatively thin dshed pressings having alternate radially extending grooves and depressions, a pair of comparatively rigid reinforcing .backings for said pressings and means for connectin each pressing to ts respective backing mem er.

2. An expanding pulley comprising in combnation a pair of relatively thin conical members having alternate radially extending,

GEOFFREY JOSEPH ABBOTT. 

